Distal mRNA localization and translation in neural stem cells of the developing brain

摘要 mRNA定位和局部翻译是保守的机制，使得能够在空间和时间上控制mRNA的表达。 基因表达。这些过程在神经系统中特别重要，在神经系统中， 基因表达影响轴突导向和突触活性。我们对mRNA的理解 定位和局部翻译依赖于体外研究。我们最近建立了一个新的听话的， 在发育中的神经系统中研究体内局部基因调控的体内范例。另外还 发现mRNA在胚胎放射状胶质细胞的基底结构中是亚细胞定位和局部翻译的 细胞（RGCs），称为endfeet。这些基底结构对于组织完整性和神经元迁移是必不可少的， 从而影响RGC在神经元生成中的中枢功能。我们开发了实时成像方法， 发现mRNA可以在RGCs中主动转运，并在基底终足中局部翻译。我们也 开发了分离RGC末端的新方法，并利用这些方法发现了末端中的局部转录组， 由RNA结合蛋白FMRP结合。我们的研究使我们假设RNA定位和局部 翻译在RGC尾足中受到内在和外在的调节，以影响信号传导， 细胞骨架在这项提案中，我们的目标是实施这些新的分子成像和基因组工具，以实现： (1)发现整个发育过程中RGC末端的局部转录组，（2）确定内在和外在的 调节RGC端足中的翻译，和（3）定义RGC端足中RNA定位的功能。 成功完成后，我们将大大提高我们对mRNA定位的理解， 通过在体内模型中研究这些过程，可以在发育中的神经系统中进行翻译。

Abstract mRNA localization and local translation are conserved mechanisms enabling spatial and temporal control of gene expression. These processes are particularly important in the nervous system, where local regulation of gene expression influences axon guidance and synaptic activity. Much of our understanding of mRNA localization and local translation has relied upon in vitro studies. We recently established a novel tractable in vivo paradigm for investigating local gene regulation in vivo in the developing nervous system. Specifically we found that mRNA is sub-cellularly localized and locally translated in basal structures of embryonic radial glial cells (RGCs), called endfeet. These basal structures are essential for tissue integrity and neuronal migration, thus impacting the central function of RGCs in neuron generation. We developed live imaging approaches to discover that mRNA can be actively transported in RGCs and locally translated in basal endfeet. We also developed novel methods to isolate RGC endfeet and used these to discover a local transcriptome in endfeet, bound by the RNA binding protein, FMRP. Our studies lead us to hypothesize that RNA localization and local translation are intrinsically and extrinsically regulated in RGC endfeet to influence signaling and the cytoskeleton. In this proposal we aim to implement these new molecular imaging and genomic tools towards: (1) discovering local transcriptomes of RGC endfeet across development, (2) determining intrinsic and extrinsic regulation of translation in RGC endfeet, and (3) defining functions for RNA localization in RGC endfeet. Successfully completed, we will have significantly advanced our understanding of mRNA localization and translation in the developing nervous system, by studying these processes in an in vivo model.